Concrete ties have been in use in some parts of the world for a long time but it is only since 1985 that they have been able to provide cost benefits for use in North America relative to wooden ties.
One advantage of concrete ties is that the rail seats can be pre assembled with only a few components to be added on site when the rail is placed in position. The difficulty with this is that the pre assembled components can become dislodged during transport and some components still have to be positioned on the rail. The rail seats usually comprises a rail pad that is positioned below the rail, an abrasion resistant plate below the pad, rail clip support shoulders on the field and gauge sides of the rail, an elastic rail clip that seats in the support shoulder and bears down on the rail base and an insulator that lies between the rail and the rail clip and the support shoulder. The support shoulders are precast in the rail tie and the rail pad is fitted between each pair. Because the rail clips and insulators contact the rail when fastened they cannot be placed in position until the rail has been placed in position on the rail seat. Rail seat assemblies of this type have been generally described in U.S. Pat. Nos. 5,110,046, 5,551,633 and 6,604,690. The rail clips in these assemblies are either installed or loose and therefore had to be assembled on site. U.S. Pat. No. 6,367,704 proposed using a modified support shoulder so that the clip could be partially installed for transport purposes where it was retained on the shoulder and then able to be fully installed when the rail was placed in position. In this arrangement the insulators still needed to be placed in position manually before the clip could be fully installed. The insulator is a one piece assembled part that lies on the rail flange to separate the rail from the clip and extends down between the rail flange and the support shoulder to provide insulation between the shoulder and the rail.
U.S. Pat. No. 5,520,330 discloses a bent rod rail clip with a two part insulator that enables the rail seat to be pre-assembled at the tie plant.
WO02/31264 discloses a rail clip that has an insulator encapsulating the toe of the rail clip that lies on the rail flange to avoid the need to insert the insulator separately.
It is an object of this invention to provide a rail clip insulator that enables easier assembly of a rail seat without compromising rail fastening performance.